1. Field of the Invention
This invention relates to improved outsoles for shoes, especially athletic shoes, and shoes embodying such outsoles.
2. Discussion of Related Art
Athletic shoes typically comprise a soft fabric or leather upper, an outsole including a treaded or cleated lower surface, an inner sole upon which the foot rests, and a midsole positioned between the outsole and the inner sole.
The midsole of a conventional athletic shoe is generally formed from a flexible, resilient, relatively soft material, to permit the shoe to absorb shock that results from impact of the foot with the ground. A typical outsole is made of a higher density, tougher, more rigid material to provide basic support for the shoe and foot as well as greater wear and tear. Despite its greater rigidity, the outsole also must be generally somewhat flexible. This form of flexible construction is necessary to facilitate ease of movement of the foot during certain athletic motions. A problem often arises, however, in that such a resilient, flexible structure may fail to give adequate support to the foot during certain types of activities.
This problem is especially prevalent in cleated shoes used in football and soccer which typically comprise a substantially flat outsole having cleats attached to or molded into the heel and toe portions thereof. The width of the outsole is narrowest at the arch, and typically flares out both forwardly and rearwardly to the ball of the foot and the heel, respectively. When the weight of the wearer is brought to bear on the toe and heel portions of such a shoe (where the cleats are normally located), the mid-portion of the outsole, having no cleats thereat and being relatively narrow and thus weak, tends to provide very poor support for the arch of the foot, causing discomfort and, in some cases, substantial strain. Further, this weakness of the arch portion of presently available cleated shoes undesirably causes the arch portion to flex under use, thereby further weakening the shoe where it least needs weakening.
Orthotic inserts have become popular, especially among serious runners, in order to provide a better fit with the substantially flat insoles of their shoes. Such an insert comprises a custom molded, generally soft body, whose upper surface conforms precisely to the contour of the bottom of a foot of the individual wearer. Such inserts may also improve stability. One orthotic insert used in an athletic shoe is set forth in U.S. Pat. No. 4,235,028 to Riggs.
While orthotic inserts perform a useful function, they are not without their drawbacks. Being made of a soft resilient material, their ability to combat sagging arches is limited. They may shift out of position during use, causing discomfort and impeding motion of the foot. They also add additional weight to each foot, a distinct disadvantage in many athletic activities. Furthermore, the orthotic insert, being custom made, must be purchased at substantial cost, adding additional expense to the cost of the footwear.
Various shoe structures have been devised for the purpose of providing adequate support for the foot. For example, U.S. Pat. No. 2,403,442 to Klaus discloses a sport shoe including an arch support molded within the insole thereof. While this shoe may provide adequate arch support, the structure of the shoe includes an outsole, an insole, and an arch support molded within the insole. These components must be assembled to each other during manufacture of the shoe, adding to the cost of the end product.
It is also well known to provide foot support by means of a molded sole or insole having an upper surface contoured to conform to the shape of the bottom: of the foot. Such soles and insoles are typically bulky, inflexible and comprise a lower surface which is itself treaded or adapted to be secured to a treaded outsole. For example, molded soles are disclosed in U.S. Pat. No. 3,552,039 to Fukuoka and U.S. Pat. No. 3,875,689 to Frau Tomas. These soles are relatively thick and heavy, having a slab-like, inflexible configuration. While each apparently provides support for the foot, due to their relatively heavy and inflexible structures, neither is suitable for active use, such as in athletics.
U.S. Pat. No. 4,224,750 to Delport discloses a metatarsal arch support having an upper surface with a special, molded shape and a flat lower surface adapted to be secured to an outsole of a sports shoe. The outsole may include cleats of various types. This shoe allegedly provides better support for the foot by positioning cleats or spikes in critical positions on the outsole. However, the arch support is relatively thick and therefore adds undesirable weight to the sports shoe.
U.S. Pat. No. 4,288,929 to Norton et al. discloses a polyurethane control device for an athletic shoe positioned between the upper and sole in the heel region. The device includes a flat base and side walls extending around the heel on the periphery of the base, and is designed to control pronation.